Food production has been shown to have considerable negative impacts on the environment. A means to reduce this is to choose organic products when shopping for food. Through the case of the EcoPanel, a web application prototype that visualises the organic proportion of the household’s food shopping, the thesis explores the intersection between design, reflection and sustainable food shopping practices. In order to contextualise the role of the EcoPanel, the text discusses the concept of food shopping practice, both from the perspective of social practice theory (SPT), and the more focused food choice perspective. The studies show that it is fundamental to understand the complexity of choosing food, and the habitual aspect of practice, in order to understand the role of reflection in food shopping practice, and consequently the role of a tool for reflective decision-making, like the EcoPanel. We have used a research through design approach to develop the EcoPanel prototype. In an iterative process we probed how the EcoPanel could be designed to be as relevant and accessible for the users as possible. Essential in the process were the iterative user feedback sessions. The way in which the users answered the questions from the sessions formed the guiding principles for the development of the design. A central question in the thesis is to explore in what ways the users’ access to their individual sustainable grocery data provided by the EcoPanel affects their food shopping practices. The studies include monitoring sixty-five users of the EcoPanel over five months, a survey regarding aspects of lifestyle and attitudes to food, and interviews with ten of the users. The long-term study shows an increased organic purchase level (17%) for the EcoPanel users in comparison to the reference group. We also see that when the users receive feedback on their organic food purchases through the EcoPanel, they can make more reflective decisions. This is shown to be highly relevant and creates meaning for the users in several different ways. From this result, in combination with the result of the long-term study, we can conclude that the EcoPanel contributes with support for more sustainable food practices. The last question in the thesis is to understand how SPT can be useful for design practice. SPT shows a view that goes beyond the traditional interaction perspective, and points to the importance of approaching complex issues, such as sustainability challenges, with an awareness that also includes social and cultural aspects of the context. As well as this view being pertinent when approaching sustainability issues, it also provides value to designers in their emerging roles of dealing with more socially embedded concerns, such as social innovation and design for public policies. / <p>QC 20160311</p>